What is delta t in heating. Temperature graph of the heating system: getting acquainted with the operating mode of the central heating system. Regarding savings on recycling

What laws govern changes in coolant temperature in systems? central heating? What is it - the temperature graph of the heating system is 95-70? How to bring heating parameters into line with the schedule? Let's try to answer these questions.

What it is

Let's start with a couple of abstract points.

• With change weather conditions heat losses of any building change after them. In frosty weather, in order to maintain a constant temperature in the apartment, much more thermal energy is required than in warm weather.

Let us clarify: heat costs are not determined absolute value air temperature outside, and the delta between the street and the interior.
So, at +25C in the apartment and -20 in the yard, heat costs will be exactly the same as at +18 and -27, respectively.

• The heat flow from the heating device at a constant coolant temperature will also be constant.
  A drop in temperature in the room will increase it slightly (again due to an increase in the delta between the coolant and the air in the room); however, this increase will be absolutely insufficient to compensate for the increased heat losses through the building envelope. Simply because the current SNiP limits the lower temperature threshold in an apartment to 18-22 degrees.

An obvious solution to the problem of increasing losses is to increase the temperature of the coolant.

Obviously, its increase should be proportional to the decrease outside temperature: the colder it is outside, the greater the heat loss will have to be compensated. Which, in fact, brings us to the idea of ​​creating a specific table for reconciling both values.

So, the temperature graph of the heating system is a description of the dependence of the temperatures of the supply and return pipelines on the current weather outside.

How everything works

There are two different types graphs:

1. For heating networks.
2. For indoor heating system.

To clarify the difference between these concepts, it might be worth starting with short excursion into how central heating works.

CHP - heating networks

The function of this bundle is to heat the coolant and deliver it to the end user. The length of heating mains is usually measured in kilometers, the total surface area - in thousands and thousands of square meters. Despite measures to insulate pipes, heat loss is inevitable: having passed the path from the thermal power plant or boiler room to the border of the house, process water will have time to partially cool down.

Hence the conclusion: in order for it to reach the consumer while maintaining an acceptable temperature, the supply of the heating main at the exit from the thermal power plant must be as hot as possible. The limiting factor is the boiling point; however, as the pressure increases, it shifts towards increasing temperature:

Typical pressure in the supply pipeline of a heating main is 7-8 atmospheres. This value, even taking into account pressure losses during transportation, allows you to start heating system in buildings up to 16 floors high without additional pumps. At the same time, it is safe for routes, risers and connections, mixer hoses and other elements of heating and hot water systems.

With some margin, the upper limit of the supply temperature is taken to be 150 degrees. The most typical heating temperature curves for heating mains are in the range 150/70 - 105/70 (supply and return temperatures).

House

There are a number of additional limiting factors in a home heating system.

• The maximum temperature of the coolant in it cannot exceed 95 C for a two-pipe and 105 C for.

By the way: in preschool educational institutions the restriction is much more stringent - 37 C.
The cost of reducing the supply temperature is to increase the number of radiator sections: in northern regions countries where groups in kindergartens are literally surrounded by them.

• For obvious reasons, the temperature delta between the supply and return pipelines should be as small as possible - otherwise the temperature of the batteries in the building will vary greatly. This implies rapid circulation of the coolant.
  However, too rapid circulation through house system heating will lead to the fact that the return water will return to the route with an exorbitant high temperature, which is unacceptable due to a number of technical limitations in the operation of thermal power plants.

The problem is solved by installing one or more elevator units in each house, in which return water is mixed with the flow of water from the supply pipeline. The resulting mixture, in fact, ensures rapid circulation of a large volume of coolant without overheating the return pipeline of the route.

For intra-house networks, a separate temperature schedule is set taking into account the elevator operation scheme. For two-pipe circuits, the typical heating temperature curve is 95-70, for single-pipe circuits (which, however, is rare in apartment buildings) — 105-70.

Climate zones

The main factor determining the scheduling algorithm is the estimated winter temperature. The coolant temperature table must be drawn up in such a way that the maximum values ​​(95/70 and 105/70) at the peak of frost provide the temperature in residential premises corresponding to SNiP.

Let's give an example of an intra-house graph for the following conditions:

• Heating devices - radiators with coolant supply from bottom to top.
• Heating is two-pipe, with .

• The estimated outside air temperature is -15 C.

A nuance: when determining the parameters of the route and the intra-house heating system, the average daily temperature is taken.
If it is -15 at night and -5 during the day, as outside temperature-10C appears.

And here are some calculated values winter temperatures for Russian cities.

The photo shows winter in Verkhoyansk.

Adjustment

If the management of the thermal power plant and heating networks is responsible for the parameters of the route, then responsibility for the parameters intra-house network is entrusted to the housing owners. A very typical situation is when, when residents complain about the cold in their apartments, measurements show deviations from the schedule downward. It happens a little less often that measurements in thermal wells show an elevated return temperature from the house.

How to bring the heating parameters into line with the schedule with your own hands?

Reaming the nozzle

When the temperature of the mixture and return is low, the obvious solution is to increase the diameter of the elevator nozzle. How it's done?

The instructions are at the reader's disposal.

1. All valves or valves in the elevator unit (input, house and hot water supply) are closed.
2. The elevator is being dismantled.
3. The nozzle is removed and drilled 0.5-1 mm.
4. The elevator is assembled and started with air bleeding in the reverse order.

Advice: instead of paronite gaskets, you can put rubber gaskets on the flanges, cut to the size of the flange from a car inner tube.

An alternative is to install an elevator with an adjustable nozzle.

Choke suppression

In critical situations (extreme cold and freezing apartments), the nozzle can be completely removed. To prevent the suction from becoming a jumper, it is suppressed with a pancake made of steel sheet at least a millimeter thick.

Attention: this is an emergency measure used in extreme cases, since in this case the temperature of the radiators in the house can reach 120-130 degrees.

Differential adjustment

At elevated temperatures as a temporary measure until the end heating season It is practiced to adjust the differential on the elevator using a valve.

1. The DHW switches to the supply pipe.
2. A pressure gauge is installed on the return line.
   
3. The inlet valve on the return pipeline is completely closed and then gradually opens with pressure controlled by a pressure gauge. If you simply close the valve, the subsidence of the cheeks on the rod can stop and defrost the circuit. The difference is reduced by increasing the return pressure by 0.2 atmospheres per day with daily temperature control.

Conclusion

Winter and frost decorate the glass windows with carved patterns... Yes, it used to be like that. Nowadays you rarely see such a phenomenon. Progress moves forward, people come up with something new to create convenience and cozy atmosphere in the house.In in this case I'm talking about sealed double-glazed windows.

But what kind of comfort can we talk about when it’s cold in the house and you don’t want to get out from under it in the morning? warm blanket? The picture is not pleasant. In this article I will tell you how to correctly calculate the number of radiator sections required to heat a room, so that you don’t have to freeze from lack of heat on winter evenings.

Someone, as I happened to see once, makes a calculation by dividing the radiator power by square meters rooms - this is fundamentally wrong! Must be calculated based on quantity cubic meters! Ceiling height in different houses may be different. Typically from 2.5 to 3m. And this is not the limit, because some people, for example, like high ceilings.

Without unnecessary theory, it’s simple and accessible.

So we think:
length - 5m,
room width - 3m,
height - 2.5m
Accordingly, the volume of heated air can be found by multiplying these values: 5 * 3 * 2.5 = 37.5 m3

The radiator that will suit us in height, that is, will be placed under the window sill, is the one with a height of 500 mm (yours may be less). The documentation says that one section of such a radiator produces 145 W at delta T = 70 C.

145 W is enough to heat 3.6 m3 of space. We have 37.5 m3. We divide the total volume - 37.5 m3 by 3.6 m3 and get the number of sections we need.

37,5/3,6=10,417
Rounding up, we get 10 radiator sections per room.

If there are 2 windows, take two radiators of 6 sections (if there are two windows, then most likely you have this corner room and more heat will be required) if there is one window - one radiator for 10 sections.

What does "delta T" mean?

In physics, it is customary to denote the difference of any quantities, in this case the temperature difference.

dT=(T1+T2):2-T3
Where dT is delta T, T1 is supply temperature, T2 is return temperature, T3 is room temperature.

dT = (95 + 85) : 2 - 20 = 70°

That is, the temperature of the coolant (water) at the radiator inlet 95° plus coolant temperature (cooled water) at the radiator outlet 85°, the result obtained divide by 2 and subtract the room temperature - 20°.

In practice, this is, of course, unrealistic. No one waits until the water in the radiator cools down exactly 15°. There is a constant circulation. That is, delta T for a radiator is a very conventional unit and in our case it is needed only for comparing characteristics different models radiators.

There is one more important point! If your room is corner or there is a basement below you, or a roof above you, increase required amount thermal energy by a factor of 1.1 - 1.3. Personally, I think it is better to install an additional radiator section. Excess heat is easily regulated by a thermostat or a regular ball valve, but its deficiency is difficult to compensate for.

Result:
1 radiator section with a power of 145 W is capable of heating 3.6 m3.
1 cubic meter requires 40 watts of power!
If the room is corner, then for 1 cubic meter you need 44 - 52 W
That's all the arithmetic!

I decided to do it myself.
So how much heat transfer should a section take, and where can I see how much is realistic?

Answer:

Heat transfer in advertising (passport) is usually given at delta T=70 for sectional radiators. Which is practically not realistic. Since it turns out that the supply is 95, the radiator supply/return on the radiator = 95/85, the ambient air is 20 degrees.

See on the manufacturer’s website what the heat transfer is at “delta T” = 50. That is, boiler flow 75, radiators 75/65, ambient air - 20 degrees. This is not always realistic either. On radiators there may be a larger difference than 75/65. For example, 75/55

For example, consider the following mode for both the boiler and radiators (with two-pipe CO). Boiler flow 60, radiators 60/40 (average 50), air - 23. We have “delta T” = 27 degrees.

Very roughly, you can derive the heat transfer reduction coefficient (roughly, because the dependence of heat transfer on “delta T” is not linear). “Delta T”, in 70g/27g = 2.59. So reduce the advertising power of radiators, leading to the actual power output, using this coefficient.

If the radiator manufacturer provides a formula for recalculating the thermal power of radiators (like, for example, Kermi-like radiators), then the real power can be calculated yourself, using the value of the real “delta T” that you already know. Please note that the manufacturer’s radiator power table is given at a specifically indicated “delta T” degrees.

Message-question

Thank you for your answers, now I have a little idea of ​​how it all works, and sorry for the stupid questions on my part.

Now about your questions. I plan to install radiators - Bimetallic radiator RIFAR Forza 500 (nominal heat flux 202 W, volume 0.2 liters), these are available for sale at your place of residence. Quantity 56 - 60 pcs.

erikra said:

If the boiler cycles due to overheating, then lengthening the circulation “route” will do little, since losses along the length of the pipeline will be small when using polymer pipes even less, and if they are also isolated... In general, IMHO, this is not a reason...

Answer:

If they wrote that you have IMHO (you have an opinion, you can’t argue with it), then we will each remain with our own opinion.

Who would like to know in more detail about the principle of “routes”, bypass, circulation, “thermal failures” and other things, please contact me in a personal message.

erikra said:

I don’t quite understand... If “the boiler’s pump run-out has ended,” then the boiler still “doesn’t know” that it’s time to turn on from “anyone” other than the room thermostat. And installing a bypass at the end of the “knowledge” branch will not help him. And it’s easier to solve this, IMHO, by installing a room thermostat in the room that cools down faster.

Answer:

Yes, sure. A thermostat is installed in such a room, which is not equipped with thermal heads on heating devices.

BUT! The boiler does not turn on according to the room thermostat signal. Please don't be misleading. Room thermostat only PROHIBITS the boiler to operate, or removes the prohibition. And whether to turn on or not, the boiler makes a decision based on the readings of the built-in temperature sensors at the boiler outlet (supply), and a small number can also monitor not only the supply, but also the return. But this is a topic for a separate discussion for the “Gas boilers” section.

Those. The boiler automation “will never be able to know” that at the far ends of the lines it has already cooled down and it’s time to turn on. And if someone has walled up the lines in the walls or floor screed, next to the “cold bridges”, it won’t take long for the lines to freeze.

DoctorEshov, asked:

Tell me, in this scheme, why is a “hitch ride” better than an “oncoming ride”? The problem of “hitting” is that the end of the branch behind the nursery must pass through the second light - inconvenient installation.

Answer:

More precisely, not “oncoming traffic”, but a “dead-end” two-pipe system. The fact that all radiator circuits (meaning individual radiators) have approximately the same hydrodynamic resistance in the system (naturally, if the radiators are the same). That is, the “passing” two-pipe is more hydraulically balanced in itself initially. And most often it works perfectly (evenly across the radiators) even without balancing the system. By its very operating principle. But balancing should not be neglected, because gas consumption may depend on the quality of the balancing done.

And "dead end" two-pipe system initially STRONGLY unbalanced. And without balancing it does not work correctly.

And so you can hang a lot more radiators “on the road” (on one circuit). But in a “dead-end” two-pipe system, it is undesirable to make more than five radiators in one branch. Otherwise, you will have to increase the diameters of the lines beyond what is reasonable, or there will be poor balance, which may not be corrected even by balancing.

P.S. They made many “dead-end” two-pipe systems, with several dead-end branches, where there are seven radiators on one branch, twelve on the other, and fifteen on the third. And then there is talk on the forums that, they say, it’s difficult to balance a two-pipe. And of course, no balancing fittings were installed on the radiator returns.. Of course, in such an incorrectly designed and installed version, the radiators are not expected to warm up normally and uniformly among themselves. Some of them will not heat up at all or partially. An attempt to balance the system using conventional ball valves (and not special type KRPSh) on radiator returns - most often it fails, not to mention the fact that Ball Valves in half-open states they quickly fail. To understand, try using a regular ball valve to adjust the flow of water from a hose for watering flowers in pots to the desired thin stream. This will be the most a clear example, how inconvenient it is to balance systems using ball valves.

Question:

Why then does the circuit not work?:

After all, all radiators are practically the same, and the diameters of the pipes are also equal everywhere, which means that the hydraulic resistance of all sections should be the same? Or what is the reason?

Answer:

The hydraulic resistance of all sections is not actually equal. It depends on the number of radiators, the connection method, and the number of sections.

The first reason it doesn't work is the lack of shut-off and balancing valves on the radiator returns. Instead of angular shut-off and balancing valves, ordinary American angles are used.

The second reason it doesn't work is the application metal-plastic pipe on highways. More precisely, the presence of strong “narrowing” in the tees-fittings for MP in the internal passage. Thus, both mains, supply and return, were “strangled”. It would seem that an MP20mm pipe was used, equivalent in throughput steel pipe¾ inch. But in reality, due to the narrow internal passage in MP tees, throughput lines turned out to be significantly lower, even than a ½-inch steel pipe.

In MP tees 20-16-20 mm, the through passage is somewhere around 12 mm, which corresponds to a larger 3/8-inch steel pipe, or even less. Those. The throughput of the highways turned out to be approximately FOUR times less than required. The boiler pump turned out to be “choked”, and most likely a fairly large share circulates not through the mains, but through the internal “small” circle of the boiler, through the bypass valve on the bypass. If the boiler cycles very often, then, most likely, in this case, part of it circulates only inside the boiler in a “small circle”.

Perhaps there are other reasons why the system made according to the diagram above does not work, I can’t see it from here, unfortunately. The scheme itself is correct and good. But why the system itself does not work, there may be a bunch of other reasons for the failure, besides the circuit. If you looked at the photo and measured the temperature throughout the entire system at control points, then you could still guess something.

And so far, fortune-telling on the coffee grounds, sorry. It is unknown what kind of reinforcement was used, etc. and so on. Also, the installers may not have taken into account that water has inertia (momentum E = m*V), what kind of boiler piping is actually done (possibly a filter mesh, aka a mud trap is too small in diameter), etc., etc.

Here real example illiterate and competent installation. The first scheme will always work correctly. Not always in the second diagram. Those. In the diagram, a five-section radiator is unlikely to work, because it may begin to circulate backwards. But the basic diagram of these two connections is the same! In the first diagram - illiterate. On the second - competently. That is, the hydraulics of flows in the tees, as well as the inertia of water, are not taken into account.

erikra said:

Why guess then? You just need to look into the "primer book", the same Scanavi, for example. There is such a picture

These are the main circulation rings, i.e. where the calculation begins. Everything else is secondary circulation rings, i.e., those same “matryoshka dolls” that you talked about.

But there are no supply and return line rings... What kind of rings are these? Only halves. The ring includes both supply and return, and heating device... a ring, it is a ring.

So each ring is tied...

Answer:

Thank you for the diagram that clearly explains the hydraulic resistance of radiators in the “dead-end” and “passing” circuits of two-pipe heating systems. Also, this diagram clearly demonstrates the advantages of diagonally connecting radiators over lateral connections.

I’ll try to once again explain on my fingers the advantage of a “hitch ride” over a “dead-end” one, using this convenient diagram.

Water follows the path of least resistance.

Therefore, in scheme a)

water will “prefer” to go along the A-1-1"-B contour rather than along the A-7-7"-B contour, because the A-1-1"-B contour has significantly less resistance, or more correctly, hydrodynamic resistance. We also must not forget that water has mass and moves at a certain speed in the pipe, therefore it has a rather large impulse E = mV.

And all this will result in the fact that if you do not install additional resistors ( balancing valves) in these circuits and such a dead-end two-pipe cannot be balanced, then the closer to the end in the dead-end branch, the less water circulation will be. And starting from some radiators, maybe even starting from the middle of a dead-end branch, there may be no circulation at all.

In diagram b)

water “it doesn’t matter where you go,” because the hydrodynamic resistance of circuit A-1-1"-B, circuit A-4-4"-B, and circuit A-7-7"-B is the same. Therefore, such a scheme with a ride can be considered balanced if sections 1-1" (and so on up to 7-7") have equal hydrodynamic resistance, as in the above schematic diagram. In reality, radiators can have a different number of sections (or sizes); they can also have different connection(lateral or diagonal). Therefore, even when using a two-pipe scheme with a passing one, it is necessary to install balancing valves on the radiator returns (especially since such a valve also replaces ball valve and American, so it costs less money).

And these rings discussed above are not linked, but are balanced until the hydrodynamic resistance is equal to each other. This is called balancing the system.

erikra said:

About Bernoulli, is that what you're talking about?

Answer:

If anyone has such a love for single-pipe systems, then it’s better to do it this way.

At the middle branch of the PP 25mm tee, the water pressure (in dynamics, but not statically) will be less than at the middle branch of the PP 32-25-32 tee. Therefore, there will be greater pressure at the inlet to the radiator than at the outlet, which will increase circulation through the radiator. Although the 25mm PP tees shown will still “narrow” the main line and the general circulation along it. At diagonal connection, even without the narrowing in the tee shown in the diagram, due to gravity, circulation will still occur through the radiator. But naturally, it also depends on the internal hydrodynamic resistance of the radiator. For cast iron and aluminum, a bottom-to-bottom connection is also suitable, even without the shown schematic technique with narrowing (but with a decrease in heat transfer). But for steel panel radiators, you may already need to apply such a solution. Or use special fittings bottom connection“binoculars” type for single-pipe systems with adjustable bypass.

But such fittings are not at all budget-friendly in price. What to do single pipe system? In terms of materials, it will be more expensive than a two-pipe system, and will have significantly more operational disadvantages compared to a two-pipe system.

For some reason, when talking about narrowing, most masters forget (or do not know) about the corollary of Bernoulli’s law, although masters often talk about “local resistances”:

“As much liquid passes through one section of the pipe in a certain time, the same amount of liquid must pass in the same time through any other section (through a series-connected section of the pipeline).” Corollary of Bernoulli's Law.

And in a single-pipe it is a section of pipeline connected in series. Therefore, if we narrow the passage in at least one place in the single-tube circuit, we will thereby reduce the flow through the ENTIRE circuit.

erikra said:

Exactly, this is a big “jamb” of this engineer... Neither balance it, nor remove the radiator... What was he thinking?

Although, not everything is as scary as it seems. Judging by the photo, there is a chance to install, instead of these American corner valves, a corner return radiator valve. In size, IMHO, the same... or close...

Not a fact... When all the thermal heads open, it can get the same effect that it has now. It is better, after all, to install return radiator valves.

Answer:

Yes, of course it's better. But if a person does not have the desire or opportunity to reinstall the system without waiting for the end of the heating season and remain without heating for several days, then it is easier to install thermal heads. You don’t have to stop heating, drain water, etc.

Yes, it is possible that there will be no balance. But only if the power of the radiators was selected by “this Engineer” to be too small, i.e. insufficient. Only in this case the thermal heads will not begin to cover up. But even in this case, balancing can be done using thermal heads. By setting the thermal head to a lower temperature, for example in non-residential or rarely visited rooms. That is, set the thermal heads not to support 25 degrees, but up to 20, or even up to 18 (and lower until self-balance occurs).

If the power of the radiators is chosen correctly, then the thermal heads will definitely begin to “press” the flow through the radiators, thereby automatically balancing the hydraulic resistance of the circuits of various radiators with each other. And the system automatically self-balances.

Flow-through two-pipe system with associated movement of water. Or else it is called “with a Tichelman loop”. “Telescope” method (method of variable line diameter).

This hydraulic circuit has all the advantages of two-pipe systems and at the same time does not have the disadvantage associated with the inequality of pressure drops inherent in “dead-end” circuits.

Hot water from the boiler (supply) passes through a supply pipeline of decreasing diameter (the “telescope” method), from which pipes extend to the heating devices, and from them into the return pipeline, which runs parallel to the supply pipeline in the direction from the boiler, collecting the water leaving the boiler. radiators with water, and increasing in diameter (the same “telescope” method) until the last radiator. In this case, the path length passable by water, is the same for all radiator circuits.

Lines made with variable diameters are called “telescoped”. This allows you to save on the cost of supply and return lines, as well as increase the hydraulic balance of the heating system.

For example, for copper lines (by soldering), this saves almost twice more money on the pipes. Instead of 100 thousand rubles, pay only 50 thousand, is there a difference or not?

A dead-end two-pipe system with counter-movement of water in the supply and return distribution pipelines and a two-pipe flow system with associated movement of water are shown for comparison in the figures below:

The boiler is designated by the letter H, and the radiators by numbers.

I would also like to repeat that the use of a “passing” two-pipe CO (heating system), instead of a “dead-end” CO, in many cases allows you to abandon the use of hydraulic arrows (hydraulic separators), collectors and additional pumps.

Those. You can get by with just a boiler pump. That is, just use a pump of less power than would be required for a dead-end two-pipe, and even more so would be required for a single-pipe (plus a single-pipe would also require a hydraulic arrow with collectors).

And this saves on the cost of materials and the cost of installing the heating system.

Question.

The boiler is still in the project, because gas will only be available next year while it’s hanging on the electric boiler

One person recommended the 16th pipe, for a single pipe, he said it would cope (the area of ​​the 2nd floor is 100 sq.m.).

Thank you! I want to good pipe, in order to lay it down for a long time and forget it, the price is secondary. The picker's hands grow normally

Answer.

My personal preference in your case (hereinafter referred to as a wall-mounted gas boiler, but not the ancient AOGV type, with non-working automation) is a PP pipe of the PN25 SDR6 brand, reinforced, but only with solid aluminum (and not perforated or fiberglass) in the center of the pipe layer. Only if you choose this option, do not believe the sellers that stripping is not required for this type of pipe. Requires special end cleaning and special attachments for welding machine for polypropylene. But it costs only 180+250+250 rubles, so it’s not a problem.

It’s just that if you grossly violate the technology and install the above-mentioned pipe without end stripping and without special attachments, only then does delamination occur and the pipes become unusable.

hobo said:

Thank you! What about the manufacturer of PN25?

answer:

For heating, it is advisable to choose a PN25 SDR6 pipe.

I believe that most fiberglass reinforced pipes for autonomous systems heating is not suitable due to oxygen permeability. For example, PN20 SDR7.4 is intended for hot water supply systems. It is good there, but not for autonomous heating systems.

What oxygen does to components of heating systems is a well-known fact.

Another thing is that many European manufacturers have already begun production polypropylene pipes, although reinforced with fiberglass, but having a protective barrier to oxygen. Unfortunately, I personally don’t have the opportunity to assess how sprayed it is the thinnest layer barrier, effectively protects against oxygen penetration. Here, as they say, “It may help, but maybe it won’t.” The desire to play it safe for now dictates the choice in favor of pipes reinforced in the center of the layer with aluminum. Moreover, this layer of aluminum must be welded hermetically along the pipe along the aluminum butt-butt joint. And not just overlapped, as some pipe manufacturers currently practice.

Sellers are indifferent to what will happen to your heating system in a few years, and that you will have to change the boiler heat exchangers, radiators and pipes. In short, do everything again. But you can't blame the sellers for everything. Well, they are not designers, after all, but only sellers. You yourself, having the specification attached to the project, should know what you need. It is clear that lately we have been asking not the doctor what medicines to buy, but the saleswoman at the pharmacy, but you must admit, this is only our misconception, and not the mistake of the salesgirl at the pharmacy.

P.S. With my hands and nose (when the PP burns on the nozzles of the welding machine and leaves) I immediately feel whether the polypropylene is of high quality or not, and with my sense of smell I feel the fake and the “scorched” pipe. I work with fittings ProAqua, Rozma, well, if I don’t find something from the required range, then SPK (but unfortunately, for last years not very quality, but there may be fakes).

I prefer dealer ProAqua. For now, I prefer Design Group Oxy Plus, reinforced with aluminum in the center of the layer (but I don’t like their fittings). Naturally, I don’t know how the quality of these brands will be in the future.

Maybe in your region there are other respectable pipes from other manufacturers, but you understand, my choice was made based on the assortment presented in my region. You can’t try all the brands, and there are a lot of fakes.

Take only from official dealers. This is the main thing. But not in chain stores and not in construction supermarkets and construction markets. This will help you protect yourself from purchasing low-quality pipes and fittings.

Allmas said:

But in the summer, how to heat... heated towel rails?

And how will the heated floors in the bathrooms work in the summer?

Answer:

If you choose a boiler like Baxi Luna 3 Comfort Combi, or another boiler set with a boiler indirect heating(BKN) having recirculation, then heated towel rails (PS) and heated floors (TP) in bathrooms in the summer can be heated from the DHW recirculation return. This recycling will also save you a lot of money, not counting the fact that you won’t have to wait for several minutes until it comes out of the tap. hot water instead of cold.

Solto said:

Will recycling save?

Could you please support your statement with numbers?

and it is not entirely clear about the TPs, which are proposed to be installed in the DHW return in the summer.

Answer:

Regarding savings on recycling.

1. Let's calculate how long we wait until the hot water from the boiler or boiler reaches the mixer we open. In many houses, from the boiler to extreme points water supply to upper floors a lot of meters of pipelines. And we’ll also calculate how much water will flow into the sewer, and we’ll also pay for excess water, and in vain we will fill our septic tank or concrete cesspool, which also needs to be emptied for money.
2. After we waited and used hot water, the volume of water that we poured into the sewer will cool down again. And to heat this volume, either diesel fuel, gas or electricity was spent. We will throw this money down the drain every time we use hot water. And next time everything will repeat in a circle. We will pour the same already cooled water down the drain, and again we will wait until hot water comes out of the mixer.
3. Taking into account the fact that, as I already wrote (from the boiler to the far bathroom) it can be very long distance DHW pipeline, we lose nerves, comfort and time. And time is also money. Calculate how many minutes a human life lasts. Not so much.

4. When recirculating the DHW supply and return pipes, when they are completely wrapped in a jacket made of foamed polypropylene (such as 9mm energyflex), they will lose very little heat.

Regarding heated towel rails and “warm” floors.

1. There is no alternative to connecting the DHW recirculation return through the substation. If only to make an electric PS. Electric PS 220 V in the shower is extreme for me, on the verge of suicide (it could easily result in fatal electric shock). If you don’t do PS at all in the bathroom, then black mold and mildew will inevitably grow, wherever possible and wherever impossible. And the smell of stale rags will always be in the bathroom. If you install an electric exhaust fan for ventilation, then, firstly, it gets on your nerves with its noise, and secondly, it should be warmer in the bathroom than in the house, so that when you get out of the bathtub or shower while steaming, you will not They would have time to freeze before rubbing themselves with a towel. A forced ventilation an electric exhaust fan in the bathroom leads to a draft in the bathroom. That is, don’t chatter your teeth when getting out of the shower in the breeze. By the way, the SanPin standard for bathroom temperature is plus 25 degrees.

2. And nothing prevents you from installing the same collector- mixing unit warm floors. Thanks to this, heated floors will function not only in heating season, but all year round. Where else can you attach the TP mixing unit so as not to turn on the heating in the summer?

Allmas said:

Yes, I would like DHW recirculation, convenient thing and not very expensive.

If it can power a 11.2 sq.m. transformer substation. m. in the summer it would be great.

I think it was necessary to separately output the TP in the bathroom of the first floor (one of the USHP collector circuits) - it would be possible to launch it in the summer...

Answer:

AND, this is not to mention the fact that the secondary heat exchanger of any double-circuit boiler Compared to a combination, a single-circuit boiler + BKN fails very quickly (and for some reason always in the coldest weather, when the system is very easy to defrost. And during this period, it is extremely difficult to find a serviceman for boilers for repairs. Unless, for an astronomical sum, much more than in summer).

Yes, and change it because of the quality of what comes cold water, every three years the heat exchanger will add up to the cost of a new double-circuit boiler after a couple of repairs. Moreover, with each such repair, you will be forced to remain not only without hot water supply, but also without heating.

And also, not to mention the savings on hot water, and comfort due to circulation, and the fact that in the summer you won’t have the smell of rotten rags in your bathrooms, and there won’t be black mold and mildew, which is extremely harmful to health.

Also, with the “native combination” boiler + BKN, hot water can never run out, and you don’t have to wash off the soap in the shower ice water. Since the boiler is 32 kW, in conjunction with a NATIVE boiler (with a heat exchanger of at least 24, at least 48 kW) it works perfectly in FLOW mode. Therefore, it is not necessary to buy BKN from 200 liters. About 70 liters is quite enough.

And one more extremely useful point in the “native” connection of the boiler with the BKN. When taking a shower, you won’t have to swallow legionella from the hot water supply (it smells like a public toilet and essentially the same contents). You can simply program the boiler so that at night once a day it brings the temperature in the BKN to plus 65. And this, coupled with recirculation, will sterilize both the BKN and the entire DHW pipeline, to the recirculation return point.